668140609 has 2 divisors, whose sum is σ = 668140610. Its totient is φ = 668140608.

The previous prime is 668140597. The next prime is 668140699. The reversal of 668140609 is 906041866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 395890609 + 272250000 = 19897^2 + 16500^2 .

It is a cyclic number.

It is not a de Polignac number, because 668140609 - 2⁷ = 668140481 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (668140699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334070304 + 334070305.

It is an arithmetic number, because the mean of its divisors is an integer number (334070305).

Almost surely, 2^668140609 is an apocalyptic number.

It is an amenable number.

668140609 is a deficient number, since it is larger than the sum of its proper divisors (1).

668140609 is an equidigital number, since it uses as much as digits as its factorization.

668140609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 40.

The square root of 668140609 is about 25848.4159862843. The cubic root of 668140609 is about 874.2237944678.

The spelling of 668140609 in words is "six hundred sixty-eight million, one hundred forty thousand, six hundred nine".